UDP-glucuronosyltransferase (UGT) enzymes enhance the polarity of steroid
hormones by catalyzing their conjugation with the sugar group from
UDP-glucuronic acid.
General function
Enzyme, Transferase
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Steroid metabolism
Comment
Barbier O, et al reported that the androgen-conjugating uridine diphosphoglucuronosyltransferase-2B enzymes are differentially
expressed temporally and spatially in the monkey follicle
throughout the menstrual cycle.
Previous results have shown that the monkey is a suitable
animal model to study steroid glucuronidation in steroid target tissues. In
humans, as in the monkey, the main androgen metabolites found in the
circulation are 5 alpha -androstane-3 alpha ,17 beta -diol-glucuronide and
androsterone glucuronide, and high levels of androsterone glucuronide were
also measured in human follicular fluid. Ovarian androgens play a significant
role as precursors for estrogens and may modulate the recruitment and growth
of follicles. To analyze the expression pattern of UGT2B enzymes involved in
androgen metabolism throughout the menstrual cycle, cynomolgus monkey ovaries
were collected during the mid and late follicular and luteal phases.
Microsomal proteins and total RNA were analyzed for UGT2B expression in the
whole ovary. Western blot and specific RT-PCR analyses demonstrated no
significant changes in the expression of UGT2B protein or transcripts during
the menstrual cycle. Immunocytochemistry analysis showed that UGT2B proteins
are expressed in the cytoplasm of thecal and granulosa cells of growing
follicles. Interestingly, the thecal cells of secondary follicles and of
corpus luteum were extensively stained, whereas luteal granulosa cells were
not labeled.